Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative procedure for various hematological malignancies, bone marrow failure syndromes and inherited metabolic disorders. The application of allogeneic HSCT is limited by donor availability such that only approximately one-third of the otherwise appropriate candidates have suitably matched family donors. Alternative donors include mismatched family members or matched unrelated donors, but these approaches are often complicated by an increased risk of graft-versus-host disease (GvHD) and a prolonged and cumbersome search and procurement process. In addition, far fewer subjects of racial minorities find suitable human leukocyte antigen (HLA)-matched donors.